The present invention relates generally to a radio telephone, such as a radio telephone operable in a cellular communication system. More particularly, the present invention relates to a frequency equalizer, and an associated method, for the receiver portion of the radio telephone. Selected portions of a signal representative of a receive signal received by the receiver portion of the radio telephone are amplified at selected amplification levels. The resultant acoustic signal formed by the radio telephone is caused to be of improved tonal characteristics.
A communication system is operable to communicate information between a transmitting station and a receiving station by way of a communication channel. A radio communication system is a communication system in which the communication channel by which information is communicated between the transmitting and receiving stations is formed upon a portion of the electromagnetic spectrum. A cellular communication system is exemplary of a multi-user, radio communication system.
Two-way, telephonic communication, analogous to the telephonic communication conventionally permitted pursuant to a wire line telephonic system, is possible by way of a cellular communication system. That is to say, a radio telephone is used to originate a call, or at which to terminate a call, in a manner analogous to operation of a conventional, wire line telephone.
To originate a call, a user of the radio telephone enters, by way of a telephonic keypad, the digits forming a telephone number of a terminating station. Once entered, the telephone number is transmitted by way of a communication channel to network infrastructure of the cellular communication system. The network infrastructure is, in turn, connected to a public-switched telephonic network. The call request originated at the radio telephone is routed therethrough to the terminating station. Subsequent to call set-up procedures, a call connection is thereafter effectuated, thereby to permit telephonic communication between the originating and terminating stations.
A call originated at a radio telephone is analogously also possible with another radio telephone. That is to say, the telephone number associated with the terminating station formed of a terminating radio telephone is entered by the user of the originating radio telephone. And, the call request is transmitted over the communication channel, to the network infrastructure, then the public-switched telephonic network, and thereafter through additional network infrastructure, over a communication channel, to be terminated at the terminating radio telephone.
A call is terminated at a terminating radio telephone by entering the telephone number associated with the terminating radio telephone at an originating station. A call request is routed through the public-switched telephonic network, network infrastructure of a cellular communication system, and upon a communication channel, thereafter to be received at the terminating radio telephone. Subsequent to call set-up procedures, two-way, telephonic communication is permitted.
Because uplink signals originated at, and downlink signals terminated at, the radio telephone are transmitted upon a radio communication channel, such signals must be of characteristics to permit their transmission upon the respective radio channels. Viz., uplink signals transmitted by the radio telephone must be converted into a form to permit their transmission upon a radio communication channel. And, downlink signals received at the radio telephone must be converted into a form to permit their transmission upon a radio communication channel.
A radio telephone includes a receiver portion operable to receive a downlink signal transmitted thereto. The receiver portion converts the downlink signal into electrical form down-converts the downlink signal from a radio frequency to a baseband-level, and demodulates the baseband-level signal. Once demodulated, the signal is transduced by a speaker, or other acoustic transducer.
The bandwidth of the acoustic signal generated by the acoustic transducer of a conventional radio telephone is sometimes on the order of about three kilohertz. The audio signals generated by the audio transducer of a conventional radio telephone are typically of substantially fixed characteristics. While the amplitude of an audio signal generated by a radio telephone sometimes can be altered, such as by way of a volume control, the tonal characteristics of the audio signal generally otherwise are unchangeable.
Different users of a radio telephone might have different aural capabilities. That is to say, different users of the radio telephone have differing capacities of detecting component portions of the audio signal at various bandwidth-frequency regions of the audio signal. Alteration of the tonal characteristics to selectively amplify selected bandwidth-frequency regions of the audio signal would facilitate user detection of the audio signal.
Also, selective alteration of the tonal characteristics of various bandwidth-frequency regions of the audio signal would also make the audio signal appear to the user to sound better. For instance, some users prefer to hear audio signals containing pronounced bass components; some other users prefer to hear audio signals containing pronounced treble components.
A manner by which to selectively alter the tonal characteristics of an audio signal generated by a radio telephone would therefore be advantageous.
It is in light of this background information related to audio signals generated by a radio telephone that the significant improvements of the present invention have evolved.
The present invention, accordingly, advantageously provides an audio frequency equalizer, and an associated method, for a radio telephone. Improved tonal characteristics of an audio signal representative of a receive signal received at the radio telephone is possible by amplifying selected portions of a signal representative of the receive signal at selected amplification levels.
In one implementation, a user of the radio telephone is able to select from amongst several groups of preset amplification levels by which to amplify a signal, prior to transducing the signal into acoustic form. The amplification levels of each group define equalization curves by which to amplify a signal received by the radio telephone, prior to transducing the signal into audio form. The tonal characteristics of the audio signal are thereby selectable by the radio telephone user, and an equalization curve appearing xe2x80x9cto sound the bestxe2x80x9d can be selected by the user. Appropriate selection of the amplification levels forming a group which defines an equalization curve, which causes, e.g., high-treble, or high-bass, tonal characteristics to be exhibited by the resultant audio signal.
Values of the preset amplification levels of the groups of amplification levels are stored in a memory device, such as an EEPROM (electrically erasable programmable read only memory). The values of the amplification levels of a selected group defining a selected equalization curve are retrieved and applied to control operation of the frequency equalizer, thereby to form a signal, when transduced by an acoustic transducer of desired tonal characteristics.
Selection is made, for example, by way of a user interface of the radio telephone utilizing a menu-driven display caused to be displayed upon a user display of the radio telephone. The user of the radio telephone selects the tonal characteristics of the audio signal by entering appropriate commands on an input actuation keypad of the radio telephone. When formed, preset amplification levels are stored in a memory element, the menu-driven display permits a user selection of a selected group of preset amplification levels to cause the frequency equalizer to form the equalization curve associated therewith. In another implementation, the user selects the amplification levels by way of the user interface at which different bandwidth-frequency regions are to be amplified.
Because the tonal characteristics of the acoustic signal generated by the radio telephone is user-selectable, the radio telephone can be personalized in a manner believed by the user to form acoustic signals of tonal characteristics most desired by the user.
In these and other aspects, therefore, a frequency equalizer, and an associated method, is provided for a radio telephone having a radio receiver. The frequency equalizer is coupled to receive an electrical signal representative of a receive signal received by the radio receiver. The electrical signal is defined by a signal bandwidth wherein the signal bandwidth is divisible into bandwidth frequency regions. The frequency equalizer selectively amplifies the electrical signal at selectable amplification levels. Each bandwidth frequency region into which the signal is divided is amplified at a separately-selectable amplification level.
A more complete appreciation of the present and to the scope thereof can be obtained from the accompanying drawings which are briefly summarized below, the following detailed description of the presently-preferred embodiments of the invention, and the appended claims.